Bench Grinder Vibration

[Daniel2]

Hello all,
As per the title really.
I bought a mid range bench grinder which, from the box, ran beautifully smoothly without
a hint of vibration. Subsequently it was wonderfully quiet as well.
It's one with a wire brush on the lefthand side and a grinding wheel on the right.
For reasons I cannot fathom, I saw fit to remove the grinding wheel, then put it back on again.
Now I have terrible vibration, making an awful racket, to the extent that I'm even rather nervous using it.
I'm assuming it's a balancing issue, maybe ?
Does anyone have any realistic ideas on how to rectify this ?

Thanks in advance.

 

[GarF]

Trial and error. Make some reference marks on the wheel, washer and spindle before you start.
Good luck

 

[Phill05]

Hi Daniel,
Take it off again and check if the two paper packing one each side is properly in place (not wobbling from side to side) if correct put it back together and tighten it up and try it, if it is out of round you need a diamond to rub across to put it back in round that should sort it for you.

 

[Daniel2]

Hi Daniel,
Take it off again and check if the two paper packing one each side is properly in place (not wobbling from side to side) if correct put it back together and tighten it up and try it, if it is out of round you need a diamond to rub across to put it back in round that should sort it for you.

Massive heartfelt thanks Phill.
It was indeed well out of round. I've given it a serious dressing with a
coarse diamond plate and it's made a huge difference.
I never knew that it could make so much difference, although, I suppose,
it's kind of obvious when you think about it. Afterwards.;;!!
Thanks so much

 

[Phill05]

Another tip, If your have a stone cutting company handy to you go along and ask if they have any broken Diamond tips off the saws they throw away, braise onto a strip of steel and put it at the side of the grinder for truing up next time save using a plate.

 

[Inspector]

Another tip, If your have a stone cutting company handy to you go along and ask if they have any broken Diamond tips off the saws they throw away, braise onto a strip of steel and put it at the side of the grinder for truing up next time save using a plate.

I do something similar. I have one drill bit from a rock drill used to make holes for blasting rock. Probably few and far between in your area but it has nice big diamonds. A more common and easier to obtain is the blade from a concrete/road saw, the big ones they walk behind. When you see a crew sawing a sidewalk, road, or plant floor for new machines (my source) ask them if they have any old blades. They might just give you a couple (400mm to 600mm across). Then you can saw from the gap in each tooth to the hole arbor with a cutting wheel in an angle grinder or a plasma cutter if you have access to one. *** it into a handle and you have a wheel dresser and a lifetime supply of spares for you and your buddies.

I was taught to install new wheels or correct a bad set to remove one and dress the remaining bone until round and running smooth. Mark it, the washers, end of shaft and remove it. Then put the second wheel on and dress it. Return the first wheel with everything lined up again and then do a final dressing of both wheels and it will be running vibration free. The reason for dressing them separately is the other wheel's vibrations can influence the one you are trying to work on.

Pete

 

[Phill05]

Nice one on cutting the blade into strips, not heard of that, I did some work on design and used a cnc to cut stone and the blade guy would come into retip the big blades 6 foot + dia and he would hot up a worn tip and hit it off put a new one on, when he left I would collect the tips for the boss and a few for me.

 

[Ttrees]

Been meaning to address my wheels also.
Some folk suggest making a bushing for the wheels.
Still need to get myself a dressing tool,
I used a lump of cement with some steel in it the last time, worked better than some random stone picked off the ground,
I might have compared some types of stone, if the cement wasn't handy which just about done the job, took a while and messy.

Best free thing you might have already may be an old broken wheel.
Love to hear some more frugal solutions.

Thanks
Tom

 

[dizjasta]

Been meaning to address my wheels also.
Some folk suggest making a bushing for the wheels.
Still need to get myself a dressing tool,
I used a lump of cement with some steel in it the last time, worked better than some random stone picked off the ground,
I might have compared some types of stone, if the cement wasn't handy which just about done the job, took a while and messy.

Best free thing you might have already may be an old broken wheel.
Love to hear some more frugal solutions.

Thanks
Tom

 

[AES]

All very good points above. But one VERY important consideration - for "next time".

When the grinding wheel is off, make up a small loop of string, run loop through the centre hole, hang wheel/loop free in one hand then "strike" the wheel (GENTLY) with something metallic - a screwdriver will do. You should hear a quite bright single ring tone (little or no reverberation). If you hear a dull "thunk" then the wheel is cracked, and please, please, pretty please (!), straight into the bin with it.

Reason? A circular saw blade (just as an example), and a grinding wheel wizz round and round at a good rate of knots. UNLIKE a circular saw blade (and lots of other things) which basically consists of a metal disc, a grinding wheel is really only a lot of "stones", "glued together" in a mould. IF cracked and it lets go, then the damage could be absolutely horrendous - to the shop, to any tools & work nearby, even to you and anybody else within range!

Back years ago in my apprenticeship we were shown a film (no videos in those days!) of an exploding wheel and the results are not only horrendous but also happen in a (very) "split second"! That's why in industry, no one is allowed to mount/dismount grinding wheels unless they've been on an approved course.

The approved course bit obviously does NOT apply in the case of a home workshop, and by the sound of things, the wheel you remounted and dressed is NOT cracked (otherwise you would have probably known about it by now)!!!!

But PLEASE, "next time" do that above crack check - I saw that exploding wheel film almost 60 years ago now and the scene remains etched in my memory.

Ditto the above "ring check" when buying a new wheel - even take the string loop with you and test it with your car key (or something) if buying from a shop.

NOT trying to be a scary old granny, just safe

P. S. Axminster Tools do a cheap wheel dresser (if you can't source a freeby as above). It's a chunk of hard grey "stone" about a 2 inches square in section and about 8 inches long. If I remember correctly it cost me about a fiver about 10 years ago. I also have a "diamond star wheel" type dresser but the above "Axi stone" comes into regular use, the star wheel only now and then. Works very well, is safe, and IMO, v good value for money.

HTH

 

[Daniel2]

@AES Thanks for the advice. Taken on board.

 

[Sideways]

Why I will never buy from Record Power again.

I had one of their bench grinders new and found the wheels siezed on the spindles as they had been damp and rusted. I had to literally hammer the wheels off. After sending the whole thing back under warranty with a clear explanation, someone in customer services sent me the cleaned and reassembled grinder back with the same wheels fitted .
I knew exactly how much of abuse it took to get them off so I removed and threw them straight in the bin rather than gamble.

 

[carpenteire2009]

I bought a cheap second hand bench grinder years ago and decided to clean it up. The original wheels while worn still had plenty of life in them. Once I'd cleaned up the motor, guards etc I turned my attention to the wheels which were grooved, out of round and unbalanced. With help from a you tube video and some online tutorials I worked out how to balance the wheels with strips of paper under the flange washers. Once this was done a quick dressing with an Axminster dressing diamond tool and a devil stone the job was done. Straightforward but time consuming. The true test was turnin on the machine and turning it off after a minute or two. When prperly balanced the wheels take nearly 2 minutes to "spool" down, a good test of balance!

 

[Inspector]

Beg to differ but a 2 minute spool down is an indication of good bearings. Good balance shows as a bench/stand with no/ or minimal vibrations. Stuff nearby not rattling etc.

Pete

 

[AES]

+1 to the above. A long run down time not only shows the bearings are good (or not) but also the heavier the wheel the longer the run down - in general terms anyway.

BUT if your run down (however long it lasts, within reason) doesn't start to sound a different tone at any stage, and/or as Inspector says, doesn't start to rattle other (not-fixed) stuff on the bench, THEN you can say you've got pretty good balance - both dynamic AND static.

 

[clogs]

dont think anyone has said/noted.....
when doing work on the grinder, relacing stones and even a wire brush PLEASE stand to one side when starting up.....
NEVER in front untill ur sure all is working well....
also I'd like a pound for every one that turned up at my place asking me to remove the ring nut from a 9" grinder....
they need to be tight but not mad tight.....
another fav gripe is those who use a thin cutting wheel with the ring nut on the wrong way round.....grrrrr....
when I change blades/stones on hand held grinders I ALWAYS run them up the first time at arms length and away from me...
luckily now most machine die when u let go of the trigger...

 

[AES]

ALL very important safety points clogs, thanks for the reminder.

May I also add one further very important one:

When refurbishing a damaged wheel, as the OP has done, (OR when buying new) please, ALWAYS before letting it spin up to speed, remove it from the spindle, "suspend" it from a loop of string through the centre bore, then while it's hanging free, tap it gently with a screwdriver or something light and metal. You should hear a slight but distinct "ring tone". If it just goes "thunk" then it's cracked, and NO questions, into the bin it goes - it's cracked.

Please remember that unlike a circular saw blade (just an example) a grinding wheel is really only "a load of stones/grit" all "glued together" in a mould. They therefore have no inherent strength (like a steel disc for example) and if cracked they CAN (and do sometimes) let go with what could be life-threatening injuries. Yes, even a little home workshop tiddler.

I saw a film of one as part of my training, and believe me it's something I'd never want to see in real life.

 

[Fergie 307]

And if the wheels are enclosed partially as most are then if it does let go the covers direct any debris straight out the front, or at you! Personally if a wheel was that badly out of balance or worn I would just replace it. I would also second the earlier comment about being overtightened. Unfortunately some people seem to think the only way to tighten any fastener is as tightly as humanly possible, often with fairly disastrous consequences.

 

[AES]

And if the wheels are enclosed partially as most are then if it does let go the covers direct any debris straight out the front, or at you! Personally if a wheel was that badly out of balance or worn I would just replace it. I would also second the earlier comment about being overtightened. Unfortunately some people seem to think the only way to tighten any fastener is as tightly as humanly possible, often with fairly disastrous consequences.

YES. There IS a reason for even the cheapest of cheapos having METAL guards around the wheels, not "just plastic"!

P.S. I see from the rest of this thread that I have - inadvertently - posted the same tip about ditching cracked wheels (and how to check them) TWICE in the same thread. Thanks to those who have "thanked" me for those posts but it really was NOT my intention to post precisely the same tip TWICE in the same thread. Forgive me, yet another sign of further onset of my "old woman-itis".